package com.hongframe.raft.util;

/**
 * fork form com.alipay.sofa.jraft.util.Ints
 *
 * @author 墨声 E-mail: zehong.hongframe.huang@gmail.com
 * create time: 2020-06-10 09:30
 */
public class Ints {

    /**
     * The largest power of two that can be represented as an int.
     */
    public static final int MAX_POWER_OF_TWO = 1 << (Integer.SIZE - 2);

    /**
     * Returns the {@code int} value that is equal to {@code value}, if possible.
     */
    public static int checkedCast(final long value) {
        final int result = (int) value;
        Requires.requireTrue(result == value, "out of range: " + value);
        return result;
    }

    /**
     * Returns the {@code int} nearest in value to {@code value}.
     */
    public static int saturatedCast(final long value) {
        return value > Integer.MAX_VALUE ? Integer.MAX_VALUE : value < Integer.MIN_VALUE ? Integer.MIN_VALUE
                : (int) value;
    }

    /**
     * Fast method of finding the next power of 2 greater than or equal to the supplied value.
     *
     * If the value is {@code <= 0} then 1 will be returned.
     * This method is not suitable for {@link Integer#MIN_VALUE} or numbers greater than 2^30.
     *
     * @param value from which to search for next power of 2
     * @return The next power of 2 or the value itself if it is a power of 2
     */
    public static int findNextPositivePowerOfTwo(final int value) {
        return value <= 0 ? 1 : value >= 0x40000000 ? 0x40000000 : 1 << (32 - Integer.numberOfLeadingZeros(value - 1));
    }

    /**
     * Find the next larger positive power of two value up from the given value.
     * If value is a power of two then this value will be returned.
     *
     * @param value from which next positive power of two will be found
     * @return the next positive power of 2 or this value if it is a power of 2
     */
    public static int roundToPowerOfTwo(final int value) {
        return 1 << (32 - Integer.numberOfLeadingZeros(value - 1));
    }

    /**
     * Is this value a power of two.
     *
     * @param value to be tested to see if it is a power of two
     * @return true if the value is a power of 2 otherwise false
     */
    public static boolean isPowerOfTwo(final int value) {
        return (value & (value - 1)) == 0;
    }

    private Ints() {
    }

}
